Method of preparing road-surfacing compositions in situ



Sept. 24, 1929. s. E. FINLEY 1,729,573

METHOD OF PREPARING ROAD SURFACING CO MPOSI'fIONS IN SITU Filed Nov. 15, 1928 2 Sheets-Sheet 1 ATTORNEYS P 24, 1929- I s. E. FINLEY 73 METHOD OF PREPARING ROAD SURFACING COMPOSITIONS IN SITU Filed Nov. 15, 1928 2 Sheets-Sheet 2 Lye/1 for ATTORNEYS Patented Sept-1Z4, 1929 I PATENT OFFICE s n: n. FINLEY, or ATLAN A, enomm METHOD PREIP AR II NG ROAD-'SURF.AGI|ING- COMPOSITIONS IN SI'IU Application filed Hovember 15, 1528, Serial No. 819,555.

X This invention relates to a method for.

- preparing and manufacturing. in place on road surfaces, compositions or combinations of uniformly mixed aggregate or solid materialand bituminous binder, of which each element ofthe aggregate is completely coated with the binder, thus producing a mixture or composition which is. in efl'ect', bituminous concrete. which. upon being laid and properly compacted. Will mature mto-wearmg surfaces of the highest stablllty, smoothness,

durabihty and waterproofness.

Suitable apparatus for carrying out the method is illustrated in the accompanying drawings, in which Fig. 1 isra perspective view of said apparatus associated with atank wagon or truck. such as is commonly employed forspraying binding media on roads.

blade.

Fig. 2 is a plan view showing the preferred arrangement of the excavating and mixing blades and associated spraying means.

Fig. 3 is a perspective view .of the rear Fig. l is an" end elevation of the forward blade and spray header illustrating the action of thebladc in raisingand tumbling the aggregate and the spraying of the latter with the binding medium. I

Referring to the .drawings', l-indicates a tank vehicle for containing the. binding medium. usually in the form of either a bituminous cement containing a hydrocarbon cht-backor li'quefier, or a highly heated 'bitumen. to be distributed upon and admixed with the aggregate or solid material, the ve' hicle preferably being of the type illustrated in my prior Patent No. 1.397,045.dated November 15. 1921, from. which the manifold or distributor bar has been removed and replaced by a special form of distributor or spray .bar. to be hereinafter describe'd, and

which is connected to 'the tank by a pipe 2.

. Secured to and forming a rearward extension of the chassis frame of the Vehicle is a platform 3, from which is adjnstably suspended a special arrangement of scrapers or blades, associated with the mechanism for spraying the binding medium onto the ag gregate or solidmaterial, while the latter is being operated upon by. the scrapers in the manner and form hereinafter described. Pivote'd to the framework or platform 3' are two angular arms 10,10,to the lower ends of which is rigidly secured a scraper or blade 11 having a detachable and renewable cutter element 12 fastened toits lower portionpthe bl de as a whole being ,curved downwardly an forwardl and being dis- .posed transversely of the ongitudinal axis of the vehicle and at an angle of approxl mately 30 to said axis. Each of the arms 10, 10is connected to operating mechanism. mounted on. the top of the platform 3, so

that these arms may befrais'ed and lowered 65.

independently to properly adjust the cutting edge of the blade 11 with respect to the road surface over which the tank vehicle travels.

N This adjusting mechanism may be of any of the preferred forms commonly employed 7 in adjusting theblades of road scrapers or. drags and, as illustrated. each adjusting ,device comprises a pedestal 13 fastened to the top of the platform 3, in the upper part of which is mounted a stub shaft 15 carrying a 7 worm 16 secured to a hand wheel 14, the .worm engaging a-worm wheel 17 journaled in the pedestal13 and having secured to one of its faces a-lever arm 18, the outer end of which is connected by a. link 19 to the correspondingpivoted arm 10. Itwill be apparent that. by operating the hand wheels 14, the blade 11 may be raised and lowered to a uniform extent throughout its length, with respect to the road surface. or either end of vehicle and at an angle of aproximately 60 V to the longitudinal axis of blade 11. the relation of the blades being clearly indicated in I Figs. 1 and 2. The blade 11 is provided-(With a removable late 12' at its lower edge. to

*' permit said p ate being replaced. when it -becomes worn or damaged. The end of the blade 11' nearest to the blade 11 is provided with an adjustable section 11, which may be raised and lowered by means of register ing bolt holes 11 and 11 and bolts 11, as

indicated in Fig. 3. The purpose of this adjustable end section 11 is to direct the material discharged from the end of blade 11- into engagement with the rear blade 11, the section 11 being secured to the end of the blade 11., so that the lower'edge of said section will clear the surface of the road outside the line of action-of the scrapers.

The adjustment of the blade 11' relative to the road surface is effected by means similar to those employed in connection with blade 11,. each of the arms 10' being connected by a link 19 with a lever 18' secured of the blade 11' are independent, it will be bars 22 and 23;

apparent that said blade 11 may beadjusted to correspond with the adjustment of the forward blade 11.

Mounted in front of each of the blades 11 j and Y11 and parallel with the latter are spray bars 22 and 23 provided with spaced spray nozzles 26, .Which direct the sprays of bind: ing medium downwardly and rearwardly toward the faces of the respective blades. The spray bars are connected to the discharge .pipe 2 leading to, the tank containingthe heated bitumen. As a matter'of convenience, thespray bars 22 and 23 are connected by cross pipes 20 and 24, each supplied with a valve 21 and 25, respectively, and are also connected at. their converging ends so as to equalize the distribution of the bitumen delivered bythe pipe 2 to the respective spray The operation of the apparatus, as described, is as follows: The forward blade 11 is adjusted so that its lower cutting edge penetrates to the desired depth in the material forming the surface of the road, so that the blade will excavate, raiseand tumble the e n B solid-materialof the road surface 1n a loose rollingmass that is moved or advanced longitudinally of the blade and continuously discharged from the rearwar'dly inclined edge of said blade and, while the solid material a is parallel with the lower edge of blade 11,

so that said blade 11 receiving the road ma-,

terial discharged from the end of blade 11 will continue the lifting and'tumbling operation on the loose materialand advance the latter transversely of the roadway in the reverse direction, as compai'ed with the transverse movement imparted to the material by the blade 11. During this continued tum-- tute a bituminous concrete wearing surface for the road.

The method is particularly adapted to the manufacture or production of road surfacmg compos tlons n whlch the solid constituents are taken fromcthe road surface and form the wearing surface of the old' road. The method is especially adapted to surfacing roadways which have been constructed of such material as gravel, clay-gravel, sandclay, sand-gravel, chert, top soil,-macadam, shell, or other similar forms or combinations of inorganic material, generally designated as aggregate. Such roadways contain, within their structure, some or all of the aggregate required to produce the desired result under the present method. The method is susceptible of scientific, accurate vand definite application in producing a properly balanced admixture of aggregate and binding medium, because prior to the manufacture or formation of the composition'directly at the,

place offuse of the la'tter, a careful screen analysis is made of the material in the roadwayand, if it: is found deficient. in any desired' size'or quality'of aggregate, this defi clency 1s remedied by addlng the desired ma-' terial before mixing with the bitumen. Also the proper quality, grade and quantity of the binding medium best suited to the particular form of the aggregate is determined by engineering practice and experience and the dc livery of the binding medium to the aggregate regulated accordingly.

- It will be noted that not only mass of aggregate in front of the forward blade 11 will be lifted, rotated and tumbled, butthat each particle in the mass is also rotated and is individually exposed, ultimately, to direct contact with the spray of bitumen until, as the action is continued a sufiicient length of time, every particle will be fully coated on all sides. It will also be understood that, due to the angularity of the axis of the blade to the center line of the roadway, the mass in front of the blade will gradually .travel along the face of that blade in breaking whorls beginning at the outer end of the blade 7 the entire I and continuing until contact with the blade 11 is lost at the rear end of the'latter, the rotation of the mass being in a clockwise direction and at the discharge end of the blade the niatbrial is delivered to the second or rear blade where the operation is repeated, but that the direction of rotation of the mass and the individual particles is reversed or anti-clockwise and the progression 'of the mass by the rearward inclination of the blade is in a reverse direction across the line of travel of the machine At the discharge end of the forward blade 11, the material is delivered in a windrow and much of the material therein would escape the second or rear blade, but for the auxiliary sfection'or extension ll 'on the latter, which is adjusted to a proper height to clear the adjacent section of the road which is not affected by the blades, so that said auxiliary section will deliver the entire body of mixed material discharged from the front blade to the rear blade without gathering any new material from the roadway lying belowthe extension.

To illustrate the use of this method on given type'of roadway consider a gravel roadway which has ravell'ed or scoured off 'at' the surface and which it is desired to replace with a bituminous concrete wearing surface The cause of the deterioration of the origmal road surface is largely due to the removal of the fine binding material by tratficandweather' conditions, includ.1n'g wind and rain.

pose that an analysis of the aggregate'on the surface of the road before treatment discloses 705 2 of aggregate will pass a 1' screen and be retained on a 1 screen and that the remaining 30% will pass through a A" screen and will be retained on a 10 mesh screen. This combination of aggregate is'deficient in fine material, if the toughest and most wear resisting paving surface is to result from the application of the present method. This deficiency may be made up. by adding approximately enough fine aggregate, such as sand and impalpable powder, so that the resulting mass will contain to of the material coarser than /1; 25% to 40% of material between and that which will pass a 200 mesh screen; and 3% to 5%. ofmaterial fine enough to pass a 200 mesh screen. :After adding this new material to that already upon the roadway, the whole is bladed, raised and tumbled by the operation of the successive blades until a substantial uniformity of distribution of the various sizes of the solid material throughout the mass is effected, and

each individual particle or. element of the solid material is thoroughly and completely coated with the binding medium. By means of similar analyses and syntheses, any standard mixture of aggregates may be produced with accuracy, the manner of making such analyses and determining .the quantity and character of aggregate and binding medium Supt6 add to produce the desired mix is a simple problem of calculation familiar to engineers and operatives skilled in the art of producing asphaltic-concrete pavements or roadways.

As stated hereinbefore, this method is especially adapted to surfacing roadways which furnish within themselves some or all of the desired aggregate, but it is not confined to the treatment of such roadways, as it may be used to advantage in the production of all types of pavements in which a complete coating of the aggregate at the place of application to the roadway is desirable. Consider, under this type, an asphalt macadam road to be treated according to the present method. Asphalt macadam is constructed of alternate Payers of stone and asphalt, the coarser layer of stone at the bottom, and with each successive layer composed of finer aggregate. Under the prior method of constructing this type of roadway. the first or lower layer of such stone isusually between 2' to 2 in diameter. This layer is spread dry and un coated to a depth of 2 to 3" and then coated from above with asphalt. During this coating'process, the stones do not move and the asphalt penetrates only for a certain depth of the stone course. After the application of the asphalt coating, one-half inch stone is castover the coated surface of the larger tion method, cannot be fully coated with asphalt and it is common knowledge that many of the stones are not coated at all. particularly those-in the lower portion of the course,

at many are only partly coated and that none of them are completely coated with the asphalt, so that a complete asphaltic binding of the aggregate throughout the course is im possible of realization; This deficiency of the.

asphaltic bondhas been the primary cause of the disintegration of bituminous or asphaltic macadam roadways under the stresses of traffic and weather and constructing engineers are constantly struggling to effect the better distribution of the binding medium throughout the aggregate and thereby increase the.

cementitious bond among the elements of the aggregate as far as possible, so that the disintegration of the wearing surface of the road will be reduced to a m1n1mum. However, the

a coating and cementing of all of the elements of the aggregate, even under the most careful modes of application of the binding medium heretofore available, leaves much to be desired in the matter, of inherent strength and wear and weather resisting qualities invarious sizes of the aggregate are uniformly inability of the penetration method to secure distributed throughout the mass, and, when the resulting mixture or composition is applied to the road surface and properly compacted, practically all of the voids in the aggregate are filled with the binding material, which cements the elements of the aggregate together into a substantially homogeneous mass.

It is well known that, when loose aggregate is spread upon a road site, there is a tendency of the aggregate to stratify or segregate according to thevarious sizes employed. ,as the material is cast and worked into place and this condition of segregation according to size is prevalent in practically all of the old types of roads hereinbefore referred to and is one of the outstanding objections of these roads, because the 'fine material s'coursoff under the wheels of trafiic or is washed away by water or blown away by the wind, so that the road loses the mechanical bonding effect of this lost fine material.

'The method involved in the present invention obviates this difficulty, in that it gathers the aggregate'from the old road surface and remixes it to substantial r'miformity of distribution of the various elements, with or without the'addition of further aggregate, as circumstances may require, before the entire quantity of binding medium necessary to effect the ultimate cementitious bond is applied. The essential novelty of the invention, in so far as the method is concerned, residesin tlie simultaneous raising, tumbling and rotating of a mass of aggregate taken from the road surface and advanced laterally with respect to said surface and spraying the tumbling and laterally moving body of aggregate wlth a bituminous bindlng medium during the multifarioust movements of the mass and the individ-- ual elementsthereof until all of said elements arecompletely coated with the bituE men and enough of the'la-t-ter is supplied to the aggregate to producea concrete mixture in-which all of the solid elements are efiectively bonded and are uniformly distributed throughout the mixture or composition, so that the latter is in ideal condition to be spread upon the road and compacted by rolling or equivalent operations into a firm, selfsustalning, wear resisting and weatherproof road surface. In addition to the advantages hereinbefore enumerated, the method results in a better product at a lower cost than is possible of attainment with the same materials applied by the methods hereinbefore in vogue. more particularly thecentral plant mix in which the ingredients are incorporated into the composition by expensive imachinery and heavy labor cost and transported through varying distances to the place'of application; and the straight penetration method in which the coarser aggre ate is first spread upon the roadway, worked to The practice of applicants method, however, as hereinbefore described, removes the plain cause of this preference and by the application of this new. penetration method produces a type of asphaltic concrete, which, when laid and matured, is equal to plant mixed pavements in all points of compariofstability.

v lVhile the invention has been described with particular reference to the utilization .ofthe aggregate or solid material from road surfaces, it will be understood that both the method and apparatus find an especially efficacious' application to the preparation of new bituminous concrete mixtures in place. This application of the invention involves son andis superior to the latter in the matter I the dumping or spreading of the mineral (aggregate, in suitable form, onto the road surface and then lifting, tumbllng andspraying the aggregate. with the binding me dium, as hereinbefore described,until all of the elements of the aggregate are completely coatedwith the binding medium and the resultant mixture of aggregate and binding medium is comparable to the bituminous concrete produced by the standard hot-mix methods in central plants, the instant invention, however, producing these desirable results at a great saving in cost, particularly of labor and time. a

While the invention is not limited to any particular type or condition of bituminous binding medium, in many cases, it will be found advantageous to employ a bituminous cement containing a hydrocarbon cut-back or liquefier, which is more or less volatile, so that the entire operation may be carried outwith relatively cold materials, thereby avoiding the necessity of heating the binding medium at a central plant and transporting the same in tank wagons to the plate et appvhhcation. i

atI claim is: e K

1. The method of preparingroad surfacing compositions of aggregate and a binder in situ, which comprises continuously and repeatedly lifting and tumbling the aggregate above the road surface and simultaneously spraying saidaggregate with bituminous binding medium. i

2. The method of preparing road surfacing compositions of aggregate and a binder in situ, which comprises continuously lift ing, tumbling and moving the aggregate transversely of the road, and simultaneously spraying said aggregate with bituminous binding medium.

- 3. The method of preparing road surfacing compositions of aggregate and a binder in situ, which comprises continuously lifting, tumbling and moving the aggregate transversely of the road in one direction,

-' then reversing the transverse movement of the aggregate in another zone of action and continuing the lifting and tumbling, and simultaneously spraying the aggregate with bituminous binding medium during the continued movement of said aggregate.

4. The method of preparing road surfacing compositions of aggregate and a binder in situ, which comprises continuously excavating the solid material from the road surface for a predetermined depth, lifting, tumbling and progressing said material transversely of the road, and simultaneously spraying-said material with bituminous inding medium. v

5. The method of preparing road surfacing compositions of aggregate and a binder in situ, which comprises continuously excavating the 'solid material from the road sur-' face for a predetermined depth, lifting. tumbling and progressing said material transversely of the road in one direction, then reversing the transverse movement of the material in another zone of action and continuing the lifting and tumbling, and simultaneously spraying the moving material with bituminous binding medium.

In testimony whereof I afiix my signature.

SAM E. FINLEY. 

